Maxene Andrews, one-third of the boogie-woogie Andrews Sisters, is singing the praises of staying youthful by staying active. "People say to me, `When are you going to retire, Maxene?' I say, `Well, when I retire, you'll only know I'm retired when you see them carrying me off the stage,' " the 72-year-old singer said during a visit this week to Nebraska. While in the Nebraska she will make speeches, including one at a dance to raise money for senior citizen centers. "I love doing these things," Andrews said. "I talk to them (senior citizens) about not getting old, if you know what I mean. Just because you've passed that mark, you don't have to think that the world is leaving you behind."